Cable’s Seismic Vulnerability In Cable-Stayed Bridges Under Corrosive Service Environment

Cable-stayed bridge is a major type of long-span bridges, very significant for transportation. The safety analysis and design for cable-stayed bridge is an important part in current bridge engineering. Corrosion may significantly affect the performance of cable-stayed bridge in use. It will weaken the cable cross section and decrease the bearing capacity. The cross section attenuation caused by corrosion will remarkably decrease the security of the cable under the action of earthquake, and so far, a lot of study concentrates on structural level or rigid components, however, investigate focusing on safety of corroded cables is lack, and calculating corroded cable capacity has no mature method.In this paper, a study about cable corrosion and seismic response is made, in terms of performance and vulnerability. The details are listed as follow:A method that could consider the stress, temperature, corrosion environment and randomness comprehensively is proposed through simulating the corrosion environment parameters for cable under service; Introduce a parameter for corrosion cable section gradient based on the theory of whole-life design. A method that could combine the statistical principle and accelerated corrosion test is proposed, to gain the whole-life time correlation curve for this parameter. It provide basis and reference for cable life estimating and performance researching; Considering the pitting issue and non-equivalent radial corrosion, present the modified Daniel model based on probability analysis to analyze the bear capacity of corrosion cable. Gain the demand value probability distribution of corrosion cable through seismic response analysis, and set up a method based on probability method to get cable seismic vulnerability.The result of analyzing cable seismic vulnerability through the corroded cable seismic vulnerability analysis methods shows that the seismic vulnerable possibility of corroded cable has big difference with the that analyzed by the method considering cable keeping intact in service time. The risk of seismic damage of cable should not be neglected in critical corrosion condition. That illustrates the capacity weakening of cable should be taken into consideration in aseismic design of cable-stayed bridge servicing in ocean environment and other corrosive environments.